Using a newly developed totally implanted, pulsed Doppler ultrasonic flowmeter, we will measure hepatic blood flow in the dog, at rest, during exercise and after feeding. We will, then, evaluate the changes in hepatic blood flow occurring during the induction of cirrhosis of the liver by dimethylnitrosamine and the consequent development of portal hypertension. In addition, further calibration studies of the flowmeter will be performed and an analysis of the portal vein flow waveform will be started.